Laboratory and imaging features of kidney involvement in autoimmune pancreatitis: incidence, correlation, and steroid therapy response.

AIM: Autoimmune pancreatitis (AIP) is a rare subtype of chronic pancreatitis. AIP has been suggested to be complicated by tubulointerstitial nephritis or glomerulonephritis, implying that the kidney is involved as a phenotype of IgG4-positive multi-organ lymphoproliferative syndrome; however, the clinical significance of this novel entity is not well-defined. METHODS: We conducted a retrospective cohort analysis of 47 (male, 39; female, 8) AIP patients. RESULTS: The patients (mean age, 70.3 +/- 9.5 years) had a mean observation period of 4.1 years. Before treatment, renal dysfunction with an eGFR of 30 and 15 ml/min/1.73 m2 developed only in 10.6% (5/47) and 2.1% (1/47) of the patients, respectively. Nevertheless, urinary N-acetyl-beta-D-glucosaminidase and alpha1-microglobulin levels were elevated in 78.6% (11/14) and 30.8% (4/13) of the patients, respectively. Renal involvement in contrast-enhanced CT imaging was present in 18.2% (8/44) of the patients and was associated with proteinuria (p = 0.04) and a decrease in eGFR (p < 0.01). Furthermore, a follow-up CT study (mean, 545 days) revealed improved kidney lesions in 80.0% (4/5) of the patients after oral corticosteroid administration. In contrast, first-time kidney involvements appeared newly in 3.6% (1/28) of the patients after steroid therapy for nonrenal AIP symptoms, and in 14.3% (1/7) of the patients under no specific therapy (p = 0.02). CONCLUSION: Although severe renal failure develops rarely in AIP patients, renal abnormalities have been significantly detected by biochemical and radiological tests. Oral corticosteroid administration, even when not targeting symptomatic nephropathy, can treat and prevent kidney involvements in AIP.

Effects of nocturnal oxygen therapy on sleep apnea syndrome in peritoneal dialysis patients.

UNLABELLED: Sleep apnea syndrome (SAS) is common in patients with end-stage renal disease (ESRD). Although the treatment of choice is continuous positive airway pressure (CPAP) particularly for obstructive SAS, long-term compliance is not satisfactory. We investigated the effectiveness of nocturnal oxygen therapy on sleep apnea and autonomic nervous dysfunction in peritoneal dialysis (PD) patients with SAS. METHODS: 40 patients on PD in our outpatient clinic were screened for SAS by pulse oximetry. We set the indication for nocturnal oxygen therapy at 4% oxygen desaturation index (4% ODI; defined as the number of falls of oxygen saturation > or = 4% per hour) > 5 or average nocturnal saturation < 95%. For SAS patients, 2 l per minute of oxygen was given during sleep and polysomnography was performed before and 1 month after oxygen administration. The heart rate variability was analyzed to assess autonomic nervous activity. RESULTS: 23 patients fulfilled the indication for oxygen therapy and 11 patients agreed to participate in the study. After oxygen therapy, the apnea-hypopnea index (AHI) and the frequencies of hypopnea and central apnea were significantly decreased (AHI: from 31.1 +/- 8.8 to 12.7 +/- 8.5, p < 0.01; hypopnea: from 19.5 +/- 4.3 to 3.5 +/- 3.2, p < 0.01; central apnea: from 4.0 +/- 4.0 to 0.8 +/- 1.2, p < 0.05), whereas that of obstructive apnea was not changed. An analysis of heart rate variability showed that oxygen therapy did not alter autonomic activity after 1 month of oxygen therapy. CONCLUSIONS: Nocturnal oxygen therapy decreases hypopnea and central apnea in PD patients with SAS. Nocturnal oxygen therapy may be useful for the treatment of SAS in PD patients, particularly when central apnea and hypopnea are predominant.

Immunohistochemical localization of latent transforming growth factor-beta binding protein in IgA nephropathy.

It has been demonstrated that cultured mesangial cells (MC) express latent transforming growth factor (TGF)-beta binding protein (LTBP) mRNA, and that LTBP might be essential for the extracellular matrix (ECM) accumulation stimulated by TGF-beta in cultured MC. We performed a study to test the pathophysiological role of LTBP in mesangial ECM accumulation in human glomerulonephropathies. The expression of LTBP in 64 renal biopsies of patients with renal diseases was examined by immunohistochemical staining with the specific antibody raised against human LTBP. The biopsy specimens were divided into three groups: Group 1, IgA nephropathy; Group 2, IgA negative mesangial proliferative glomerulonephritis, which mainly consisted of diabetic nephropathy and lupus nephritis; and Group 3, non-proliferative nephropathy, which consisted of minimal change and membranous nephropathy. Immunohistochemical staining of LTBP was significantly detected in mesangial/paramesangial area of glomerulus in Group 1, but not observed in Group 2 or Group 3. The intensity of staining was well related to the grade of mesangial ECM accumulation in Group 1. These findings suggest that the LTBP-TGF-beta complex may play a pivotal role in ECM accumulation in IgA nephropathy, and that modification of LTBP-ECM interaction might provide a new therapeutic strategy against the progression of glomerulosclerosis.

Tyrosine-kinase dependent TGF-beta and extracellular matrix expression by mechanical stretch in vascular smooth muscle cells.

Vascular hypertrophy, which is characterized by proliferation of vascular smooth muscle cells (VSMC) and accumulation of extracellular matrix (ECM), is a major pathological change in blood vessels after chronic exposure to hypertension. Blood pressure is transmitted to the arterial walls and counterbalanced by mechanical stress, leading to stretching of circumferentially oriented VSMC, which may play some role in the pathogenesis of vascular hypertrophy. The present study was designed, therefore, to investigate the effect of mechanical stretch on the expression of ECM components and transforming growth factor-beta (TGF-beta), a potent stimulator for ECM production, and to examine the signal transduction mechanisms of the induction of TGF-beta in cultured rat VSMC. VSMC were subjected to cyclic stretch to provide a maximal elongation of 20% at a rate of 60 cycles per minute for up to 24 h. Mechanical stretch stimulated TGF-beta1 mRNA expression in a time- and elongation-dependent manner. Indeed, the secretion of TGF-beta proteins into the culture media was increased after stretch. Stretch also stimulated mRNA expression of the ECM components, type I and type IV collagen, and fibronectin, which was largely inhibited by addition of neutralizing antibody against TGF-beta. The tyrosine kinase inhibitors genistein and herbimycin A blocked the induction of TGF-beta1 and type I collagen by stretch, while protein kinase C inhibitors, the calcium channel blockers nitrendipine and gadolinium, or Ca removal from the media had no effect. These results suggest that stretch-induced, tyrosine kinase-mediated autocrine/paracrine production of TGF-8 may play a critical role in the progression of vascular remodeling associated with high blood pressure.

[TGF-beta gene expression in mesangial cells].

TGF-beta recently has been shown to inhibit mesangial cell growth and to stimulate mesangial matrix synthesis by mesangial cells. Cultured rat mesangial cells expressed 2.5 kb TGF-beta mRNA, and removal of fetal calf serum (FCS) for two days decreased the TGF-beta mRNA level, which was then stimulated by addition of 17% FCS and TPA, one of the phorbol esters, although it is also reported by others that the mRNA expression was stimulated by PDGF, EGF, or high glucose. Bioassay and immunoblot analysis showed that mesangial cells produce and secrete substantial amounts of TGF-beta but mostly in latent forms. Moreover, addition of anti-TGF-beta neutralizing antibodies augmented mesangial cell growth, indicating that the secreted TGF-beta exerts a growth-inhibitory action on themselves. Thus, TGF-beta may function as an autocrine factor in mesangial cells, and it is suggested that mesangial cells may play an important role in the pathogenesis of glomerulopathy.

[Angiotensin II and the kidney].

Angiotensin II (AngII) plays a central role for maintenance of GFR and Na balance particularly in volume depletion, when AngII preferentially increases the resistance of efferent arterioles as compared to afferent arterioles, enhancing the glomerular perfusion pressure. In addition, AngII enhances tubular reabsorption of sodium in proximal tubules directly and indirectly as a consequence of glomerulotubular balance. AngII also stimulates Na reabsorption in the collecting ducts by stimulating the release of aldosterone from the adrenal cortex. AngII augments tubuloglomerular feedback. Recently, it has been shown that AngII has a variety of non-hemodynamic effects on cell growth and differentiation as well as inflammatory responses, and it has been speculated that the increased renin-angiotensin, not only systemic but local one, may be responsible for the pathogenesis of a number of renal diseases.

Betaglycan has multiple binding sites for transforming growth factor-beta 1.

The transforming growth factor-beta (TGF-beta) binding site in betaglycan, the type III TGF-beta receptor, has been variously assigned to the C-terminal half and N-terminal one-third of the extracellular domain. In this study, we show that there are at least two TGF-beta-binding sites in betaglycan. Bacterially expressed fragments bg 1,2 and bg3, which represent the N-terminal two-thirds and C-terminal one-third of betaglycan extracellular domain, both competed for the binding of 125I-TGF-beta to mink lung epithelial cells. 125I-bg1,2 bound to immobilized TGF-beta with an affinity about 4-fold higher than bg3 had. Both bg3 and bg1,2 enhanced the bioactivity of TGF-beta. The whole ectodomain of betaglycan was more active than either bg3 or bg1,2 in the assays. The binding of 125I-bg3 to TGF-beta was inhibited by bg1,2 and vice versa. The binding of 125I-bg3 and 125I-bg1,2 to TGF-beta was also inhibited by the small decorin family of proteoglycans. These results indicate that there are at least two binding sites for TGF-beta in betaglycan and that these sites recognize the same or overlapping sites in TGF-beta.

Autocrine secretion of transforming growth factor-beta in cultured rat mesangial cells.

Transforming growth factor-beta (TGF-beta) recently has been shown to modulate mesangial cell growth and to stimulate mesangial matrix synthesis by mesangial cells. Here we examined whether mesangial cells expressed TGF-beta mRNA and secreted mature TGF-beta, and we investigated the role of TGF-beta in mesangial cell growth. Cultured rat mesangial cells expressed 2.5 kb TGF-beta mRNA, and removal of fetal calf serum (FCS) for two days decreased the TGF-beta mRNA level, which was then stimulated by re-addition of 17% FCS reaching the maximum at nine hours. 12-O-tetradecanoyl phorbol-13-acetate (TPA), one of the phorbol esters, markedly increased the mRNA level and reached the maximum at six or nine hours. Immunoblot analysis of the conditioned media using specific anti-TGF-beta 1 antibodies revealed single 12.5 kDa proteins, the size compatible with mature TGF-beta subunits. By means of bioassay using CCL-64 cell line, TGF-beta production rate by mesangial cells was estimated to be 22.1 +/- 6.5 (mean +/- SD) ng/10(6) cells/24 hours, 96% of which was in latent forms. Exogenously added TGF-beta inhibited mesangial cell growth at 10 pM or higher. Moreover, addition of anti-TGF-beta neutralizing antibodies augmented mesangial cell growth, indicating that the secreted TGF-beta actually exerted a growth-inhibitory action. In summary, mesangial cells produce and secrete substantial amounts of TGF-beta but mostly in latent forms, and the secreted TGF-beta may regulate mesangial cell growth and differentiation. We conclude that TGF-beta may function as an autocrine factor in mesangial cells.

Regulation of parathyroid hormone synthesis in chronic renal failure in rats.

To clarify the mechanism of secondary hyperparathyroidism in chronic renal failure at the parathyroid hormone (PTH) synthesis level, we measured PTH messenger RNA (mRNA) levels in parathyroid glands in a rat model of chronic renal failure. Four weeks after 7/8 nephrectomy, hyperplasia of parathyroid glands was evident and serum PTH levels were elevated. Serum concentration of calcium, inorganic phosphate, and 1,25-dihydroxyvitamin D (1,25(OH)2D) of rats with chronic renal failure were not detectably different from those of sham-operated rats. In chronic renal failure rats, PTH mRNA levels were elevated both per RNA and per DNA of parathyroid cells, suggesting increased PTH mRNA levels per cell. The elevated levels of PTH mRNA were returned to normal levels by achieving supraphysiological concentrations of 1,25(OH)2D3 given i.p. twice at 24 and 48 hours before sacrifice, although this was attended by slight hypercalcemia. A synthetic analogue of vitamin D, 22-oxa-1,25(OH)2D3, also suppressed PTH mRNA to normal levels, but without hypercalcemia. These data suggest that secondary hyperparathyroidism in early chronic renal failure may be due in part to the resistance of parathyroid cells to the physiological concentration of 1,25(OH)2D in circulation on PTH synthesis and that 22-oxa-1,25(OH)2D3 may be useful in the management of secondary hyperparathyroidism of chronic renal failure.

Redox-sensitive regulation of lox-1 gene expression in vascular endothelium.

Oxidative stress has been implicated in atherosclerosis and its underlying conditions. LOX-1 is a novel endothelial receptor for oxidized low-density lipoprotein which might mediate endothelial dysfunction and subsequent atherogenesis. In the present study, we examined LOX-1 gene regulation by oxidative stress. First, superoxide anions generated by hypoxanthine and xanthine oxidase as well as hydrogen peroxide increased LOX-1 mRNA expression in cultured aortic endothelial cells. Homocysteine, an atherogenic substance believed to exert its effects through oxidative stress, enhanced endothelial LOX-1 gene expression, which was suppressed by N-acetylcysteine. Second, rats receiving angiotensin II for 10 days manifested hypertension and LOX-1 upregulation in aortic endothelium via AT1 receptor. Tempo, a superoxide dismutase mimetic, alleviated LOX-1 augmentation induced by angiotensin II. These results indicated redox-sensitive upregulation of LOX-1 mRNA in both in vitro and in vivo systems, suggesting its potential role in atherosclerosis.

A rise in antineutrophil cytoplasmic antibody in a patient with systemic vasculitis in remission.

We report a 42-year-old man who showed alveolar hemorrhage and glomerulonephritis as well as episcleritis and skin rash. He had an extremely high titer of cytoplasm-staining antineutrophil cytoplasmic antibody (C-ANCA) and was diagnosed as having systemic vasculitis based on histological findings of kidney and skin biopsies. After immunosuppressive therapy clinical manifestations resolved within several weeks and C-ANCA titers commensurably declined. C-ANCA titers, however, increased again and remained high despite clinical remission. In general, there is a close relationship between ANCA titers and clinical activities in ANCA-associated diseases, but they displayed a large discrepancy in this patient. Indeed, the serum of the patient in remission contained the antibody against 29-kD neutrophil extracts which was detected by immunoblot analysis. These findings suggest that C-ANCA may not necessarily be, by itself, pathogenetic for the development of the vasculitis.

Anti-latent TGF-beta binding protein-1 antibody or synthetic oligopeptides inhibit extracellular matrix expression induced by stretch in cultured rat mesangial cells.

Transforming growth factor-beta (TGF-beta) is usually secreted as a large latent complex associated with latent TGF-beta binding protein-1 (LTBP-1), which is known to bind to extracellular matrix (ECM) components. Although the LTBP-ECM interaction has been suggested to play a role in the activation and biological action of TGF-beta, the precise mechanism is still unclear. In glomerular hypertension mesangial cells are believed to perceive the increased cyclic strain and we have recently reported that cyclic mechanical stretch in vitro enhances the expression of ECM components via an autocrine/paracrine secretion of TGF-beta in cultured rat mesangial cells. Therefore, in this study we examined the role of LTBP-1 in the stretch-induced, TGF-beta-mediated ECM expression. Mesangial cells expressed mRNA for short and long forms of LTBP-1 (LTBP-1S and LTBP-1L, respectively). Mesangial cells were subjected to cyclic stretch to provide a maximal elongation of 20% at a rate of 60 cycles/min for 24 to 36 hours in the presence of polyclonal antibody raised against human LTBP-1 or synthetic oligopeptides corresponding to the N-terminal portions of human LTBP-1, which may work as competitive inhibitors against the LTBP-ECM association. Both anti-LTBP-1 antibody (Ab39) and synthetic oligopeptides inhibited the stretch-induced mRNA expression of type I collagen and fibronectin in a dose-dependent manner, but the inhibition by Ab39 or the oligopeptides was recovered by adding recombinant TGF-beta. Ab39 or the oligopeptides did not change the effect of exogenously added TGF-beta, such as growth-inhibition in mink lung epithelial cells. These results suggest that mesangial cells secrete TGF-beta as a large latent complex, and the LTBP-ECM interaction may be a pivotal step in TGF-beta action and ECM accumulation, providing a new therapeutic strategy against progression of glomerulosclerosis and other fibrotic diseases.

Tyrosine kinase dependent expression of TGF-beta induced by stretch in mesangial cells.

Increased glomerular hydraulic pressure has been suggested as a major causative factor in the development of glomerular sclerosis. The elevation of glomerular pressure increases the magnitude of stretch to mesangial cells. The study was, therefore, designed to investigate the effect of mechanical stretch on expression of TGF-beta and extracellular matrix components in cultured rat mesangial cells. The results showed that mechanical stretch stimulated mRNA expression for TGF-beta1 and TGF-beta3 in a time dependent manner, and that mesangial cells secreted substantial amounts of TGF-beta proteins in response to stretch. Stretch was also shown to stimulate mRNA expression for collagen types I and IV, and fibronectin, major components of mesangial extracellular matrix. The stretch-induced mRNA expression for extracellular matrix components was inhibited by neutralizing antibody to TGF-beta. Moreover, stretch-induced mRNA expression of TGF-beta was inhibited by tyrosine kinase inhibitors, genistein or herbimycin A, whereas Ca channel blockers nitrendipine or Gd3+, and inhibitors for protein kinase A or C had no effect. These findings indicate that stretch induced TGF-beta mRNA primarily through tyrosine kinase-dependent mechanisms in cultured rat mesangial cells, and the secreted TGF-beta may play a significant role for the stretch-induced expression of extracellular matrix proteins. Our results suggest that stretch-induced TGF-beta of mesangial cells might be a mediator in the progression of glomerular sclerosis as an autocrine/paracrine factor.